Can You Solve the Equation 5^n = 80n for n?

  • Thread starter Thread starter One-D
  • Start date Start date
One-D
Messages
17
Reaction score
0
I've got a problem with this:
5^n=80n
find n!
I can't solve out this one.
thanx for ur help, I'm not sure if it's the right place for this thread.
 
Physics news on Phys.org
If n \in \mathbb{Z}, there is no such number.
 
5^x - 80*x = 0
plot it
and so far I've found 2 solutions (oh and there are no solns in Z of course)

Approximate roots are:

n=0.012759
n=3.50133
 
Last edited:
Anyway the 2 exact solutions (in real numbers) are:

n = -\frac{\text{ProductLog} \left( - \frac{\ln 5}{80} \right)}{\ln 5}

and

n = -\frac{\text{ProductLog} \left(-1, - \frac{\ln 5}{80} \right)}{\ln 5}

Which works out to 100 sf.:

n = 0.01275934595849510712320293028417381446823346765193827957982622843955432250672941443435143426214944153

And:

n = 3.501327193786496727104387840526356291207393167955463046140101380079871277483867981890189846055191784
 
and that is an 'analytical' solution?
 
thanx for ur replies
 
##\textbf{Exercise 10}:## I came across the following solution online: Questions: 1. When the author states in "that ring (not sure if he is referring to ##R## or ##R/\mathfrak{p}##, but I am guessing the later) ##x_n x_{n+1}=0## for all odd $n$ and ##x_{n+1}## is invertible, so that ##x_n=0##" 2. How does ##x_nx_{n+1}=0## implies that ##x_{n+1}## is invertible and ##x_n=0##. I mean if the quotient ring ##R/\mathfrak{p}## is an integral domain, and ##x_{n+1}## is invertible then...
The following are taken from the two sources, 1) from this online page and the book An Introduction to Module Theory by: Ibrahim Assem, Flavio U. Coelho. In the Abelian Categories chapter in the module theory text on page 157, right after presenting IV.2.21 Definition, the authors states "Image and coimage may or may not exist, but if they do, then they are unique up to isomorphism (because so are kernels and cokernels). Also in the reference url page above, the authors present two...
When decomposing a representation ##\rho## of a finite group ##G## into irreducible representations, we can find the number of times the representation contains a particular irrep ##\rho_0## through the character inner product $$ \langle \chi, \chi_0\rangle = \frac{1}{|G|} \sum_{g\in G} \chi(g) \chi_0(g)^*$$ where ##\chi## and ##\chi_0## are the characters of ##\rho## and ##\rho_0##, respectively. Since all group elements in the same conjugacy class have the same characters, this may be...
Back
Top